Sun tan is the browning of the skin as a result of sunlight exposures. Other than sun tan, sunlight can damage the skin with the potential of causing wrinkles, age spots, and even cancers of the skin. The browning of the skin is actually the result of our bodies' protective mechanism against sunlight. Exposures to sunlight could lead to DNA damage in the skin cells. In addition, exposures of the skin to the ultraviolet portion, UVA in particular, of sunlight can cause the oxidation of the melanin pigment in the skin resulting in the deepening in color of melanin in a short time and increased synthesis of melanin in skin cells after two or three days. The oxidized melanin and the increased amount of melanin in the skin cells offer protection against future exposures to sunlight by shielding the skin cell DNA from the harmful ultraviolet radiation of sunlight. The oxidized melanin and increased amount of melanin cause sun tan.
Sun tan has long been regarded as a side effect of outdoor exposures to sunlight for some people working outdoor or for travelers in some regions of the world. Appropriate clothing and hats have been worn to reduce sunlight exposures reducing the chance of sunburn, and secondarily the chance or degree of sun tanning. However, with recent lifestyle changes and changes in beauty standards, sun tan has more and more been accepted by some segments of the population as desirable nowadays. Some people even actively seek sun tan for what they perceive to be its aesthetic value. These people would deliberately increase sunlight exposures, for example by sun bathing, in order to achieve sun tanning. Because sun bathing can cause sunburn, some people may apply sunscreen that would reduce exposures to the damaging portion of the ultraviolet radiation of sunlight in order to prolong sun bathing with reduced sunburn risk.
Others may want to get sun tan with artificial means including exposures to ultraviolet radiation under UV lamps in sun tanning booths, application of skin lotions or creams containing bronzers, certain brown dyes, to stain the skin temporarily, or application of self-tanning compositions to the skin. The self-tanning compositions contain a self-tanner such as dihydroxyacetone (DHA) or erythrulose. The self-tanner chemical reacts with proteins in the dead cells of the stratum corneum to produce a brown substance. Because the dead cells are desquamated in two to three weeks, the tanning does not last long. Despite the long availability of sunless tanning products, there is a need for improved sunless tanning compositions that can produce better tanning effects. The present invention is aimed at improving sunless tanning compositions.